U.S. patent application number 14/012199 was filed with the patent office on 2013-12-26 for device for fixation of bone fractures.
This patent application is currently assigned to STRYKER TRAUMA GMBH. The applicant listed for this patent is Stryker Trauma GmbH. Invention is credited to Marcel Aeschlimann, Klaus Dorawa, Christopher Rast, Manuel Schwager, Philipp Seiler.
Application Number | 20130345764 14/012199 |
Document ID | / |
Family ID | 40253783 |
Filed Date | 2013-12-26 |
United States Patent
Application |
20130345764 |
Kind Code |
A1 |
Dorawa; Klaus ; et
al. |
December 26, 2013 |
DEVICE FOR FIXATION OF BONE FRACTURES
Abstract
A device and method for fixation of bone fractures has a bone
screw comprising a shank with a threaded end portion, on the outer
surface. The screw has a through bore with two bore portions
differing in diameter. A step in the diameter is formed between
these bore portions and is located within the end of the screw
having the thread. This step in diameter can support a metal insert
which in turn supports a polymer pin when the latter if pressurized
with a sonotrode in the bone screw. Together with an applied
ultrasonic vibration the pressure fluidizes the polymer pin and
presses the material through holes configured in the wall of the
bone screw and into surrounding bone.
Inventors: |
Dorawa; Klaus;
(Schoenkirchen, DE) ; Schwager; Manuel; (Zurich,
CH) ; Rast; Christopher; (San Diego, CA) ;
Aeschlimann; Marcel; (Ligerz, CH) ; Seiler;
Philipp; (Arboldswil, CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Stryker Trauma GmbH |
Schoenkirchen |
|
DE |
|
|
Assignee: |
STRYKER TRAUMA GMBH
Schoenkirchen
DE
|
Family ID: |
40253783 |
Appl. No.: |
14/012199 |
Filed: |
August 28, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11879045 |
Jul 13, 2007 |
8556947 |
|
|
14012199 |
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Current U.S.
Class: |
606/329 |
Current CPC
Class: |
A61B 17/864 20130101;
A61B 17/846 20130101; A61B 2017/8655 20130101; A61B 17/8685
20130101; A61B 17/7098 20130101; A61B 17/8822 20130101 |
Class at
Publication: |
606/329 |
International
Class: |
A61B 17/84 20060101
A61B017/84 |
Claims
1-15. (canceled)
16. A method for fixation of a bone fracture comprising: inserting
a bone fastener having a bore therein and a plurality of ports for
communicating between the bore and the bone across a fracture site;
inserting a polymer pin having a metal insert into the bore of the
bone fastener; ultrasonically melting the polymer pin; and forcing
the melted polymer through the ports in the bone fastener and into
the bone.
17. The method as set forth in claim 16 wherein a leading end of
the polymer pin contacts the metal insert.
18. The method as set forth in claim 17 wherein the bore of the
bone fastener has an annular step formed therein for contacting the
metal insert, the step formed adjacent to the ports in the bone
fastener.
19. The method as set forth in claim 18 further comprising mounting
the metal insert on the leading end of the polymer pin and sliding
the combination along the bore of the bone fastener until the step
is contacted.
20. The method as set forth in claim 16 wherein the force applied
to the melted polymer is constant as the melted polymer exits the
ports.
21. The method as set forth in claim 16 wherein the bore of the
bone fastener has an open end acting as one of the ports.
22. The method as set forth in claim 21 wherein the bone fastener
is a cannulated bone screw.
23. A method for fixation of a bone fracture comprising the steps:
screwing a bone screw having an axial bore therein with transverse
passageways connecting the bore with an outer surface of the bone
screw into a bone across a fracture site, the bore having first and
second diameters forming a step therebetween; combining a polymer
pin with a metal insert at a tip of the polymer pin; inserting the
polymer pin together with the metal insert into the axial through
bore in the bone screw; and pressuring and vibrating the polymer
pin, wherein the polymer pin is supported by the metal insert which
is in turn supported by a step in the diameter in the through bore,
resulting in the polymer pin being fluidized at its tip, the
fluidized polymer material being pressed out of the bone screw.
24. The method as set forth in claim 23 wherein the polymer pin is
combined with the metal insert by snap mounting.
25. The method as set forth in claim 23 wherein the metal insert
has a protruding end suitable for snap mounting and wherein the
polymer pin has a snap mounting end corresponding to the protruding
end.
26. The method as set forth in claim 23 wherein the bore has an
annular step formed therein for contacting the metal insert, the
step formed adjacent the ports in the bone fastener.
27. The method as set forth in claim 23 further comprising mounting
the metal insert on the leading end of the polymer pin and sliding
the combination along the bore until the step is contacted.
28. The method as set forth in claim 23 wherein the force applied
to the melted polymer is constant as the melted polymer exits the
ports.
29. The method as set forth in claim 24 wherein the snap mounting
comprises a slight clearance when connected.
30. A method for fixation of a bone fracture using ultrasonic
energy, comprising: obtaining a bone screw having a shank with a
first threaded end and having along a longitudinal center line
thereof an axial through bore having a first bore portion with a
first diameter and a second bore portion with a second diameter,
wherein the first diameter is larger than the second diameter and
the second bore portion is adjacent the first threaded end, and a
step is formed in the bore between the first and the second bore
portions; inserting a first end of a polymer pin into the first
bore portion of the bone screw; coupling a metal insert to the
first pin end of the metal insert having a disk-shaped first end
having a diameter smaller than the first diameter and larger than
the second diameter, the metal insert having a second end having a
diameter smaller than the diameter of the first end of the metal
insert, the polymer pin first end having a recessed bore for
receiving the second end of the metal insert, the recessed bore
having an end wall defining a base of the recessed bore, the metal
insert second end having an end face contacting the end wall of the
base of the recessed bore; and applying ultrasonic energy and
transmitting the ultrasonic energy from the metal insert to the
leading end of the polymer pin for fluidizing the leading end.
31. The method as set forth in claim 30, wherein the shank has a
non-threaded portion and the step in the through bore is located in
the threaded end portion.
32. The method as set forth in claim 30, wherein the bone screw
further comprises holes in a wall of the bore of the bone screw,
the holes are located in the threaded end portion adjacent the step
in the bore.
33. The method as set forth in claim 30, wherein the metal insert
is dimensioned so that the first end rests on the step in the bore
when the metal insert is inserted into the bore in the bone screw,
and wherein the leading end of the polymer pin is configured so
that it is insertable into the through bore.
34. The method as set forth in claim 30, wherein the disk-shaped
first end is dimensioned so that it rests on the step in the bore
when the metal insert is inserted into the bone screw bore and the
second end has a pin-shaped portion, and wherein the recessed bore
is a counterbore that is configured to receive the pin-shaped
portion on the metal insert with which it is connectable.
35. The method as set forth in claim 24, wherein the second end of
the metal insert is snapped into the recessed bore of the polymer
pin first end.
36. The method as set forth in claim 30, wherein the polymer pin
leading end has a radially inwardly tapered outer surface.
37. A method for fixation of a bone fracture using ultrasonic
energy, comprising: obtaining a bone screw having a shank with a
first threaded end and having along a longitudinal center line
thereof an axial through bore having a first bore portion with a
first diameter and a second bore portion with a second diameter,
wherein the first diameter is larger than the second diameter and
the second bore portion is adjacent the first threaded end, and a
step is formed in the bore between the first and the second bore
portions; and inserting a polymer pin into the axial through bore,
the pin having a metal insert at a first end, wherein the metal
insert comprises a substantially disk-shaped first end dimensioned
for resting on the step in the bore when the polymer pin and metal
insert are inserted into the bone screw through bore, the metal
insert has a second end including a pin-shaped portion, and wherein
the polymer pin first end has a counter bore configured to receive
the second end pin-shaped portion on the metal insert with which it
is connectable, thereafter applying ultrasonic energy and
transmitting the ultrasonic energy from the metal insert to the
first end of the polymeric pin.
38. The device as set forth in claim 37, wherein the metal insert
is dimensioned so that its first end rests on the step in the bore
when the metal insert is inserted into the first bore first portion
in the bone screw, and wherein the first end of the polymer pin is
configured so that it is insertable into the first bore
portion.
39. The device as set forth in claim 37, wherein the polymer pin
first end has a radially inwardly tapered outer surface.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application is a divisional of U.S. patent
application Ser. No. 11/879,045, filed on Jul. 13, 2007, the
disclosure of which is hereby incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The invention relates in general to sonic fusion technology,
it relating more particularly to a device and a method for the
fixation of bone fractures, with a bone screw for augmenting within
a bone.
[0003] Known from U.S. Pat. No. 4,653,489 is a system wherein a
fixation cement is introduced through a bone screw into a portion
of a bone afflicted by osteoporosis. Femoral neck fractures as well
as distal femoral fractures can be fixated by means of this
device.
[0004] The system in accordance with prior art comprises a bone
screw having a flow cavity, i.e. an axial through bore through
which bone cement can be introduced into the portion at the tip of
the screw. The bone cement is advanced by a device which is
releasably attached to the trailing end of the screw. This device
is similar to a commercially available syringe in comprising
substantially a cylindrical barrel and a plunger. The barrel forms
a cavity in which the plunger is movable to and fro.
[0005] In use of this prior art device the fixation cement is
filled into the barrel, after which the plunger is urged against
the cement. By applying manual compression force the fixation
cement is jetted into the axial through bore of the bone screw. Due
to the pressure the fixation cement is adequately fluidized so that
it can pass through the proximal end of the bone screw into the
bone, as a result of which the bone screw is augmented in the
bone.
[0006] This system has the drawback that the manual pressure
applied to the fixation cement varies, not only basically from
application to application but also during the application itself
so that the distribution of the fixation cement within the portion
of the bone at the tip of the bone screw is neither reliable nor
even.
SUMMARY OF THE INVENTION
[0007] An object of the invention is to define a device and a
method by means of which a reliable and even augmentation of a bone
screw at an implantation site in the bone can now be assured.
[0008] An aspect is achieved in accordance with the invention by
the bone screw for fixation of a bone fracture, having a bone screw
comprising a shank having a first threaded end and having along its
longitudinal center line an axial through bore having a first bore
portion with a first diameter and a second bore portion with a
second diameter, wherein the first diameter is larger than the
second diameter and the second bore portion is adjacent the first
shank end, and a step in the bore between the first and the second
bore portions. Another aspect is achieved by a method for fixation
of a bone fracture comprising the steps of screwing a bone screw
having an axial bore therein with transverse passageways,
connecting the bore with an outer surface of the bone screw into a
bone across a fracture site, combining a polymer pin with a metal
insert, inserting the polymer pin together with the metal insert
into the axial through bore in the bone screw, pressuring and
vibrating the polymer pin, wherein the polymer pin is supported by
the metal insert which is in turn supported by a step in the
diameter in the through bore, resulting in the polymer pin being
fluidized at its tip, the fluidized polymer material being pressed
out of the bone screw.
[0009] The invention will now be detailed by way of a preferred
embodiment with reference to the attached drawings in which:
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a section view of a bone screw in accordance with
one embodiment of the invention;
[0011] FIG. 2 is a detail view of the tip of the bone screw as
shown in FIG. 1;
[0012] FIG. 3 is a view of a polymer pin in accordance with one
embodiment of the invention;
[0013] FIGS. 4a and 4b are a side view and respectively a plan view
of a metal insert in accordance with one embodiment of the
invention;
[0014] FIG. 5 is a section view of a device for fixation of a bone
fracture in accordance with one embodiment of the invention, with
the bone screw as shown in FIG. 1 in which the polymer pin as shown
in FIG. 3 and the metal insert as shown in FIGS. 4a, 4b are
inserted; and
[0015] FIG. 6 is a detail view of the tip of the device as shown in
FIG. 5.
DETAILED DESCRIPTION
[0016] Referring now to FIG. 1 there is illustrated a bone screw 10
in accordance with the invention. The bone screw comprises a shank
and a thread 12 machined in an end portion of the shank, although
the thread may also cover the shank of the screw full length. In
addition, the bone screw 10 is cannulated. The cannulation is
provided along the longitudinal center line of the screw as a
through bore 11 composed of two bore portions 16, 17. Bore portion
16 comprises a first diameter and bore portion 17 a second
diameter, the first diameter being larger than the second diameter.
In addition the bore portion 16 forms the main portion of through
bore 11. In the preferred embodiment, just a small portion
adjoining the end of the shank of the bone screw in which the
thread 12 is machined is formed by the bore portion 17. The
transition from the bore portion 16 to the bore portion 17 is
formed by a step 18 in the bore 11. The step 18 in the bore forms
an annular ridge having substantially right-angled edges at the
wall of the through bore within the bone screw. The edges of the
step 18 in the diameter may be machined flat or rounded. The screw
features transverse holes 14 which extend through the wall of the
bore portion 16 to allow polymeric material within the bore 11 to
flow out of bore 11 and into the adjacent bore. Furthermore the
position of the step in diameter together with the holes in the
wall can be positioned optionally along the longitudinal center
line and thus the location of the polymeric augmentation can be
determined in accordance with the particular application and the
desired effect.
[0017] In the preferred embodiment the holes 14 may be configured
in differing directions perpendicular to the longitudinal center
line of the bone screw and arranged in the end portion with the
thread 12. Preferably the holes 14 are arranged in a region of the
end portion which also features the bore portion 16. In the
embodiment as shown in FIG. 1 two holes 14 each are configured
axially juxtaposed in the bore portion 16 and through the thread
12. Furthermore, four such pairs of holes are evenly distributed
about the circumference of the bone screw, in other words,
circumferentially spaced by 90.degree.. It is, however, just as
possible that three, four, five or more holes may be provided
circumferentially and it is not necessary that the holes
circumferentially distributed are all at same axial level. Apart
from this, transverse or longitudinal oblong holes, slots, or the
like may be provided.
[0018] Referring now to FIG. 2 there is illustrated the tip of the
bone screw as shown in FIG. 1 but on a magnified scale, the step 18
in the diameter between the bore portion 16 and bore portion 17 now
being particularly evident. Apart from this, a few of the holes 14
are shown which are configured passing through the thread 12 in the
bore portion 16.
[0019] Referring now to FIG. 3 there is illustrated a polymer pin
20 elongated in shape and slightly tapered at a conically tapered
end 22. Provided in the conically tapered end 22 of the polymer pin
20 is a concavity or counterbore 24 in the end face. The polymer
pin 20 may also be made of other materials such as for instance a
thermoplastic material suitable for augmenting a bone screw, both
resorptive and non-resorptive materials being useful.
[0020] Referring now to FIGS. 4a and 4b a metal insert is shown in
a side view and in a plan view. The metal insert features a
substantially disk-shaped end 32 and a substantially pin-shaped end
34. The disk-shaped end 32 has an outer diameter somewhat smaller
than the diameter of the bore portion 16 and somewhat larger than
the diameter of the bore portion 17. The pin-shaped end 34 is
configured so that it can be inserted into the counterbore in the
polymer pin.
[0021] In another embodiment (not shown) the metal insert features
instead of the pin-shaped end 34 a protruding end suitable for snap
mounting, the polymer pin in this case having a snap mounting end
corresponding to the protruding end. When the metal insert is snap
mounted with the polymer pin, both elements can be inserted
together into the bone screw, it being of advantage when the snap
mount comprises a slight clearance when connected. This clearance
has the advantage that when the polymer pin is pressurized it can
be better fluidized at the joint with the metal insert to thus
easier jet from the bone screw into the bone.
[0022] It is furthermore possible that the metal insert instead of
featuring a protruding or pin-shaped end has a through bore into
which a corresponding end of the polymer pin can engage. In this
embodiment the polymer material is jetted axially from the bone
screw not only through the holes 14 but also out the leading end of
the screw through the hole in the metal insert. the proportion of
the polymer material emerging from the holes and bores can be
varied by the size thereof.
[0023] Depending on the aspect concerned, a snap mount may also be
provided in combination with axial and/or radial holes, it being
just as possible, however, to configure the metal insert integrally
with the bone screw. In this arrangement the step in the diameter
between two portions of the bore is configured by a larger
difference in diameter; indeed, even an axial blind hole may be
used on the cannulation instead of the full axial through bore in
the bone screw.
[0024] The following details inserting the bone screw into a bone.
Firstly a K wire is powered up to the site in a bone at which the
bone screw is to be located. Via the K wire the bone screw is then
advanced and ultimately screwed into place until it is sited as
desired. After insertion of the bone screw in the bone the K wire
is removed. This procedure makes it necessary that the bone screw
features a full length through bore. This is a popular operation
technique because the operator can best check the position of the
screw. The K wire is also used to measure the necessary screw
length.
[0025] After removal of the K wire the passageway or through bore
11 along the longitudinal center line of the bone screw is free to
receive polymer pin 20 together with metal insert 30. Tip 34 of the
pin shaped end of metal 30 insert is inserted into counterbore 24
of polymer pin 20. Referring now to FIG. 5 there is illustrated how
metal insert 30 rests on the step formed by the step 18 in the bore
when polymer pin 20 with the metal insert 30 has been inserted
facing the direction of the tip. It is in this way that the step 18
in the diameter forms within the bone screw a counterhold for the
metal insert which in turn supports the polymer pin when the
polymer pin is pressurized and vibrated by an ultrasonic
handpiece/sonotrode which, for this purpose, is mounted on the free
end of the bone screw. The vibration and pressure generated by the
ultrasonic handpiece and applied to the polymer pin fluidizes the
polymer pin so that the material of the polymer pin emerges from
the radially arranged holes 14 into the bone. It is in this way
that the polymer pin furnishes the material for augmenting the bone
screw in the bone.
[0026] It is to be noted that the present invention is not just
limited to the indications as recited above. In other words, all
screw applications which can be supplied by cannulated screws can
be potentially supplied with the option of polymeric fastening and
thus with the device in accordance with the invention.
[0027] Although the invention herein has been described with
reference to particular embodiments, it is to be understood that
these embodiments are merely illustrative of the principles and
applications of the present invention. It is therefore to be
understood that numerous modifications may be made to the
illustrative embodiments and that other arrangements may be devised
without departing from the spirit and scope of the present
invention as defined by the appended claims.
* * * * *